Department of Microbiology and Immunology, University of Maryland School of Medicine.
Department of Biology, West Virginia University.
Genome Biol Evol. 2018 Sep 1;10(9):2292-2309. doi: 10.1093/gbe/evy159.
While typically a flea parasite and opportunistic human pathogen, the presence of Rickettsia felis (strain LSU-Lb) in the non-blood-feeding, parthenogenetically reproducing booklouse, Liposcelis bostrychophila, provides a system to ascertain factors governing not only host transitions but also obligate reproductive parasitism (RP). Analysis of plasmid pLbAR, unique to R. felis str. LSU-Lb, revealed a toxin-antitoxin module with similar features to prophage-encoded toxin-antitoxin modules utilized by parasitic Wolbachia strains to induce another form of RP, cytoplasmic incompatibility, in their arthropod hosts. Curiously, multiple deubiquitinase and nuclease domains of the large (3,841 aa) pLbAR toxin, as well the entire antitoxin, facilitated the detection of an assortment of related proteins from diverse intracellular bacteria, including other reproductive parasites. Our description of these remarkable components of the intracellular mobilome, including their presence in certain arthropod genomes, lends insight on the evolution of RP, while invigorating research on parasite-mediated biocontrol of arthropod-borne viral and bacterial pathogens.
虽然跳蚤通常是寄生在哺乳动物身上的寄生虫和机会性病原体，但在非吸血、孤雌生殖的书虱（Liposcelis bostrychophila）中发现的猫栉首蚤里克氏杆菌（Rickettsia felis）（菌株 LSU-Lb）为确定不仅宿主转移而且专性生殖寄生（RP）的因素提供了一个系统。对独特于 R. felis str. LSU-Lb 的质粒 pLbAR 的分析揭示了一个毒素-抗毒素模块，其具有与寄生沃尔巴克氏体菌株中编码的噬菌体毒素-抗毒素模块相似的特征，这些菌株利用该模块在其节肢动物宿主中诱导另一种形式的 RP，即细胞质不亲和性。奇怪的是，大型（3841 aa）pLbAR 毒素的多个去泛素化酶和核酸酶结构域以及整个抗毒素，有助于从各种细胞内细菌中检测到一系列相关蛋白，包括其他生殖寄生虫。我们对这些细胞内可移动元件的这些显著组成部分的描述，包括它们在某些节肢动物基因组中的存在，为 RP 的进化提供了深入了解，同时也为寄生虫介导的节肢动物传播病毒和细菌病原体的生物防治研究提供了新的思路。
